A direct digital frequency synthesizer (DDFS) is a digitally-controlled signal generator that may vary the output signal frequency over a large range of frequencies, based on a single fixed-frequency precision reference clock. In addition, a DDFS is also phase-tunable. In essence, within the DDFS, discrete amplitude levels are input to a digital-to-analog converter (DAC) at a sampling rate determined by the fixed-frequency reference clock. The output of the DDFS may provide a signal whose shape may depend on the sequence of discrete amplitude levels that are input to the DAC at the constant sampling rate. The DDFS is particularly well suited as a frequency generator that outputs a sine or other periodic waveforms over a large range of frequencies, from almost DC to approximately half the fixed-frequency reference clock frequency.
A DDFS offers a larger range of operating frequencies and requires no feedback loop, thereby providing near instantaneous phase and frequency changes, avoiding overshooting, undershooting and settling time issues associated with other analog systems. A DDFS may provide precise digitally-controlled frequency and/or phase changes without signal discontinuities.
With the popularity of portable electronic devices and wireless devices that support audio applications, there is a growing need to provide a simple and complete solution for audio communications applications. For example, some users may utilize Bluetooth-enabled devices, such as headphones and/or speakers, to allow them to communicate audio data with their wireless handset while freeing to perform other activities. Other users may have portable electronic devices that may enable them to play stored audio content and/or receive audio content via broadcast communication, for example.
However, integrating multiple audio communication technologies into a single device may be costly. Combining a plurality of different communication services into a portable electronic device or a wireless device may require separate processing hardware and/or separate processing software. Moreover, coordinating the reception and/or transmission of data to and/or from the portable electronic device or a wireless device that uses FM transceivers may require significant processing overhead that may impose certain operation restrictions and/or design challenges.
Furthermore, simultaneous use of a plurality of radios in a handheld may result in significant increases in power consumption. Power being a precious commodity in most wireless mobile devices, combining devices such as a Bluetooth radio and a FM radio requires careful design and implementation in order to minimize battery usage. Additional overhead such as sophisticated power monitoring and power management techniques are required in order to maximize battery life.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.